1. Field of the Invention
This invention relates to improvements in a one-way clutch used in the transmission of an automobile, an agricultural machine, a construction machine, an industrial machine or the like, and particularly the automatic transmission of a vehicle or the like, and performing the function of a backstop. More particularly, it relates to a ratchet type one-way clutch using a ratchet (pawl) in a lock mechanism and a method of manufacturing the same.
2. Related Background Art
Generally, a one-way clutch used in an automatic transmission has an outer ring and an inner ring rotated relative to each other, and a sprag or a roller for transmitting torque between the outer ring and the inner ring meshes with a cam surface provided on the raceway surface of the outer ring or the inner ring to thereby transmit rotational torque only in one direction. Also, design is made such that the outer ring and the inner ring are idly rotated in the opposite direction.
Such one-way clutches include a ratchet type one-way clutch using a ratchet as a torque transmitting member for transmitting torque between the outer ring and the inner ring. Generally, the ratchet type one-way clutch is comprised of an outer ring having a pocket in the inner periphery thereof, an inner ring disposed coaxially with the outer ring and having a notch in the outer periphery thereof, a pawl contained in the aforementioned pocket, fitted in the notch of the inner ring and bringing the one-way clutch into its locked state to thereby transmit torque between the inner ring and the outer ring, and a resilient member for biasing the pawl toward the inner ring.
FIG. 14 of the accompanying drawings is an axial fragmentary cross-sectional view of the side plate 190 and outer ring 130 of a ratchet type one-way clutch according to the prior art. A pocket 131 for containing a pawl therein is formed in the inner periphery of the outer ring 130. Also, in a state wherein an inner ring and the outer ring are combined together, the side plate 190 abuts against an axial side of the outer ring 130 to thereby regulate the axial movement of the pawl.
Further, it is conceivable to provide, as means for preventing the circumferential relative movement of the outer ring 130 and the side plate 190, a mountain portion 195 on the outer peripheral portion of the side plate 190 and a valley portion 138 in the outer peripheral surface of the outer ring 130, and fit the mountain portion 195 into the valley portion 138.
According to the above-described construction, it is necessary to provide the mountain portion 195 and valley portion 138 only for fitting the side plate 190 to the outer ring 130 in the side plate 190 and outer ring 130 constituting the ratchet type one-way clutch, and this leads to the problem that such clutch is of a shape difficult to work and the cost for the working becomes high.
In the ratchet type one-way clutch of the above-described construction, when the one-way clutch rotates in one direction, the pawl slides freely relative to the outer periphery of the inner ring and therefore, the outer ring and the inner ring idly rotate relative to each other. Next, when the one-way clutch is about to rotate in the other direction, the pawl fits in the notch and the one-way clutch assumes a locked-up state.
Usually, the outer ring of the ratchet type one-way clutch is made of aluminum, but it was not always satisfactory in respect of durability due to, for example, pivotal movement or the like repeated by the pawl in the pocket provided in the outer ring.
Also, the pawl of the ratchet type one-way clutch has a recess having a shape substantially complementary thereto, and fits in a notch formed in the outer periphery of the inner ring. However, satisfaction was not always obtained in respect to durability due to the meshing performance of the ratchet and for example, pivotal movement repeated by the pawl in the pocket provided in the outer ring.